Problem: $\overline{AB} = \sqrt{61}$ $\overline{AC} = {?}$ $A$ $C$ $B$ $\sqrt{61}$ $?$ $ \sin( \angle BAC ) = \frac{6\sqrt{61} }{61}, \cos( \angle BAC ) = \frac{5\sqrt{61} }{61}, \tan( \angle BAC ) = \dfrac{6}{5}$
Solution: $\overline{AB}$ is the hypotenuse $\overline{AC}$ is adjacent to $\angle BAC$ SOH CAH TOA We know the hypotenuse and need to solve for the adjacent side so we can use the cos function (CAH) $ \cos( \angle BAC ) = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{\overline{AC}}{\overline{AB}}= \frac{\overline{AC}}{\sqrt{61}} $ $ \overline{AC}=\sqrt{61} \cdot \cos( \angle BAC ) = \sqrt{61} \cdot \frac{5\sqrt{61} }{61} = 5$